Combined harvesters, thrashers and crop cleaners, also known as “combines” or “harvesters”, cut crop material close to the ground, gather it together, and thrash it, removing unwanted plant matter and dirt from the grains and seeds (the crop) to be harvested. Harvesters have two primary stages: the first stage (called the “crop delivery system” herein includes a header and a feeder.
The header portion of a harvester extends along the ground, engages the stalks of growing plants with a comb-like cutter bar, cuts the plants off very close to the ground, and presents the cut off plant material to the feeder. The feeder portion gathers the cut off plant material, compresses it slightly, and feeds it to the thrashing portion of the harvester.
Feeders typically include a conveyor that extends from the header portion to the thrashing portion of the harvester. This conveyor engages the mat of plant material and draws it upward from ground level to perhaps four feet above the ground where it presents the plant matter to the mouth of the thrashing section.
The thrashing section of a harvester typically includes one or two pairs of concentric cylinders that rotate with respect to each other, shredding the plant material, thereby dislodging the crop from the remaining unwanted stalks and leaves.
To thrash the plant matter effectively, the spacing of the concentric cylinders is critical. The gap between the two cylinders must be narrow enough to separate out the plant matter from the crop (i.e. the grain or seed), yet not so narrow that the thrashing elements damage the crop. In many cases, the space between the two cylinders can be as small as 1 or 2 inches, and cannot be permitted to vary more than an inch or so as the concentric cylinders rotate with respect to one another.
If the gap between the two cylinders varies over time, and becomes either wider or narrower, the harvester will cease to harvest the crop well. If the gap increases, the thrashing section will no longer separate the crop from the plant matter and the entire mass will be passed through the thrashing section, to other components expecting clean crop from the harvester. If the gap decreases, the two cylinders will not only separate the plant matter from the crop, they will actually damage the individual kernels of the crop itself thus producing a much lower quality crop.
One of the significant problems for harvesters is preventing other material such as stones from entering the crop delivery system than being fed into the thrashing section. Agricultural fields are quite commonly strewn with such objects as stones. The cutter bar of the crop delivery system is usually positioned quite closely to the ground, within one or two inches of the ground for some crops. At this height, even small stones are easily scooped up into the header section and fed along with the plant material into the feeder and thrashing sections.
Once a stone enters the thrashing section, even a small rock about two or three inches across, it can do serious damage to the thrashing section. Forced between the two cylinders the stone obstructs the passage of small ribs or fins disposed on the mating surfaces of the two concentric cylinders that separate the crop from the stalks and leaves. If the rock is large enough, it can actually jam the two cylinders, prevent them from rotating with respect to each other, and shut down the harvester. Harvesting can be delayed for several hours as the farmer works to remove the stone.
One means of protecting a harvester from stones was described in U.S. Pat. No. 6,601,372, which issued to the assignee of the present patent application. In this patent, a system for dealing with stones drawn into the crop delivery system is provided. A stone sensor such as a piezoelectric transducer is mounted in the crop delivery system to sense impacts of rocks as they are swept into the header and feeder. A microprocessor is coupled to the sensor, monitoring the signals from the sensor and determining whether a rock has entered the crop delivery system. When the signals reach a predetermined level, the microprocessor signals the operator in the cabin and signals a solenoid in a hard object removal system mounted to the bottom of the feeder. When the solenoid receives the signal from the microprocessor, it opens a door in a hard object removal system and permits the rock or other hard object that triggered the piezoelectric sensor to fall out and onto the ground.
The sensitivity of the system should be varied according to the type of crop that is being harvested. For some crops, such as soybeans, wheat, and rice, the crop and plant matter that is carried into the harvester together with the crop is soft, pliable, thin, and generates relatively little noise. In contrast to this, crops such as corn, for example, generate a lot of noise when they are drawn into the crop delivery system of the harvester. Corn plants have stalks as well as ears. The stalks are stiff and thick and the ears are hard. When the header cuts the corn plants and they fall into the header, the ears and the stalks cause a considerable amount of noise. As the ears and stalks impact the sides and bottom of the crop delivery system, they cause the piezoelectric sensor to generate sharp and loud signals similar to the signals generated by stones.
Unless the sensitivity of the stone detection system is adjusted appropriately, the microprocessor can easily confuse crop signals generated by noisy crops with signals generated by stones. For this reason, whenever the operator changes from one crop to another crop by changing the type of header used on the harvester, he should change the sensitivity of the stone detection system of the '372 patent. Not all farmers do this, however. Further, the farmers that adjust the sensitivity may not adjust it correctly. What is needed, therefore, is a system for automatically changing the sensitivity of the stone detection system based upon the type of crop that is being harvested. It is an object of this invention to provide such a system.
A wide variety of crops can be harvested by a single harvester. The chassis and thrashing elements of the harvester are typically adjustable to permitted to harvest everything from wheat to rice to soybeans to corn. No one single header can be used with all of these crops, however. For that reason, headers are made to be interchangeable. A header for one crop can be unbolted and removed from the feeder and another header for another crop attached in its place. Some of the more common headers include corn headers, grain headers, and Draper headers. Corn headers, as one might expect, are intended for harvesting corn. Grain and Draper headers are designed to harvest grass crops such as rice, wheat, and oats. These are the most common headers used on harvesters. Different headers for other specialty crops are also known and used, but in lesser numbers.
Whenever a harvester is operated with a corn header, the only crop it harvests is corn. Similarly, whenever a harvester is operated with a grain header or Draper header the only crop it harvests is a grass crop. What the applicants have devised is a system for automatically determining the type of header attached to the harvester in using that information to automatically set the sensitivity of the stone protection system at a level appropriate for that crop. By automatically sensing the type of header attached to the harvester, and automatically adjusting the stone detection system's sensitivity to stone sensor signals, the farmer is automatically assisted in selecting the appropriate sensitivity.